1. Field of the Invention
The present invention pertains to safety penetrating instruments and, more particularly, to automatic retractable safety penetrating instruments having sleeves for introduction into anatomical cavities and penetrating members with sharp tips disposed within the sleeves for penetrating cavity walls with automatic retraction of the penetrating members into the sleeves upon penetration to protect tissue and organ structures within the cavities from the sharp tips of the penetrating members.
2. Discussion of the Prior Art
Penetrating instruments are widely used in medical procedures to gain access to anatomical cavities ranging in size from the abdomen to small blood vessels, such as veins and arteries, epidural, plural and subachroniad spaces, heart ventricles and spinal and synovial cavities, with access being established via a sleeve positioned during penetration into the cavity with the penetrating instrument. Use of penetrating instruments has become an extremely popular and important first step in endoscopic, or least invasive, surgical procedures to establish an endoscopic portal for many various procedures with access being established via portal sleeves of the penetrating instruments. Such penetrating instruments typically include a portal sleeve and a penetrating member disposed within the portal sleeve and having a sharp tip or point to pierce or penetrate the tissue forming the cavity wall with the force required to penetrate the cavity wall being dependent upon the type and thickness of the tissue of the wall. Once the wall is penetrated, it is desirable to prevent the sharp tip of the penetrating member from inadvertent contact with or injury to tissue or organ structures in or forming the cavity, and a particular problem exists where substantial force is required to penetrate the cavity wall or the cavity is very small in that, once penetration is achieved, the lack of tissue resistance can result in the sharp tip traveling too far into the cavity and injuring adjacent tissue or organ structures.
Safety trocars having a spring-biased protective shield disposed between an outer sleeve and an inner trocar are marketed by Ethicon, Inc. as the Endopath and by United States Surgical Corp. as the Surgiport. U.S. Pat. Nos. 4,535,773 to Yoon, 4,601,710 to Moll and 4,654,030 to Moll et al are illustrative of such safety trocars. A trocar disposed within a portal sleeve and retractable within the sleeve when force from tissue contact is removed from the sharp tip of the trocar is set forth in U.S. Pat. No. 4,535,773 to Yoon.